Download rocks

2002 Minerals
Education Workshop
Sponsored by:
Indiana Department of Natural Resources – Division of Reclamation
November 1-2, 2002
www.caingram.com
Rocks
A rock is an aggregate of one or more minerals.
http://people.uncw.edu
Rocks
Divided into 3 main groups based on origin:
1. Igneous
2. Sedimentary
3. Metamorphic
www.travelwest.net
Igneous Rocks –
Form as a
result of cooling
& crystallization
of magma & lava
Indiana Geological Survey
Igneous Rocks
www.eos.duke.edu
 Parent rocks for all other rocks
 65% of the Earth’s crust
 Two major classifications: extrusive and
intrusive
Igneous Rocks
Classified as either:
1) Volcanic (extrusive) rocks:
Crystallize quickly in volcanic
eruptions  very small or no
crystals
www.mineralminers.com
www.mineralminers.com
www.geo.aau.dk
Igneous Rocks
2) Plutonic (intrusive) rocks:
Crystallize slowly within the earth that allows
crystals to grow
Granite
www.uct.ac.za
www.geocities.com
http://kafossils.tripod.com
Common Igneous Rocks
http://volcanoes.usgs.gov
Basalt Rhyolite
Pumice Obsidian
e
x
t
r
u
s
i
v
e
Granite
Kimberlite
i
n
t
r
u
s
i
v
e
Diorite
Gabbro
http://cwx.prenhall.com
http://cwx.prenhall.com
Identifying Igneous Rocks
 Identification is based on texture (overall
appearance of the rock – size, shape &
arrangement of mineral grains) and
mineralogical composition
• Interlocking mineral crystals
ROCK TEXTURE
IGNEOUS
Crystalline
(interlocking)
www.env.duke.edu
Modified from Indiana Geological Survey
Identifying Igneous Rocks
• Texture indicates the rate of cooling
 Phaneritic texture: coarse-grained; mineral
grains are macroscopic
www.uct.ac.za
Identifying Igneous Rocks
 Aphanitic texture: fine-grained; mineral grains are
microscopic
http://volcanoes.usgs.gov
Identifying Igneous Rocks
 Glassy texture
www.mineralminers.com
www.mineralminers.com
Identifying Igneous Rocks
 Porphyritic texture: contains at least (2) different
grain sizes
www.uct.ca.za
Identifying Igneous Rocks
 Vesicular texture: numerous cavities
http://volcanoes.usgs.gov
Identifying Igneous Rocks
 Pyroclastic
http://volcanoes.usgs.gov
Identifying Igneous Rocks
 Identification is based on texture (overall
appearance of the rock – size, shape &
arrangement of mineral grains) and
mineralogical composition
Sedimentary Rocks
www.geo.cornell.edu
Sedimentary Rocks
• Form from
weathered igneous,
sedimentary and/or
metamorphic rocks
• Weathered fragments
transported by water,
air or ice
• Can also form from
chemical processes
http://earthsci.org
Sedimentary Rocks
Ripple marks and cross-bedding
in sand dune complex
Indiana Geological Survey
Sedimentary Rocks
Sandstone bedrock
with preserved cross-bedding
Indiana Geological Survey
Sedimentary Rocks
• Generally layered
or bedded
www.geo.cornell.edu
Evaporite deposits (white deposits)
Indiana Geological Survey
Sedimentary Rocks
• Textures range from
very fine grained
to coarse grained
www.nps.gov
www.wps.prenhall.com
Sedimentary Rocks
• May contain
fossils
www.uky.edu
www.kyu.edu
www.uky.edu
www.geo.cornell.edu
www.palaeos.com
www.uky.edu
www.geocities.com/atrypa
www.uky.edu
www.geocities.com
www.uky.edu
Identifying Sedimentary
Rocks
 Identification is based on particle size,
particle shape, mineral composition and
texture
• Detrital sedimentary rocks: composed of
fragmented pre-existing rocks deposited by
water, wind or ice and cemented together by
minerals precipitated within the void spaces
e.g. conglomerate/breccia, sandstone, siltstone, shale,
mudstone
Identifying Sedimentary
Rocks
 Identification is based on particle size,
particle shape, mineral composition and
texture
• Detrital sedimentary rocks
Generally composed of a combination of
quartz, feldspar, rock fragments & clay minerals
Identifying Sedimentary
Rocks
 Identification is based on particle size,
particle shape, mineral composition and
texture
• Detrital sedimentary rocks
• Chemical sedimentary rocks
Identified mostly by mineral
composition (e.g. limestone, CaCO3)
Identifying Sedimentary
Rocks
 Clastic and nonclastic texture:
• Clastic: sedimentary rocks made up of
broken particles (all detrital rocks & some
chemical sedimentary rocks)
www.geo.cornell.edu
Identifying Sedimentary
Rocks
 Clastic and nonclastic texture:
• Nonclastic: remaining chemical sedimentary
rocks
http://earthsci.org
www.nps.gov
ROCK TEXTURE
SEDIMENTARY
www.eos.duke.edu
Fragmental
(clastic)
Modified from Indiana Geological Survey
Common Sedimentary Rocks
 Shale
 Limestone
 Sandstone
 Conglomerate
 Dolomite (Dolostone)
 Siltstone
 Breccia
wps.prenhall.com
www.rockware.com
Metamorphic Rocks
Metamorphic Rocks
(Meta = change
morph = form)
• Pre-existing rocks are converted to metamorphic rocks
by increased temperature, pressure and/or chemical
fluids
Metamorphic Rocks
• Derived from pre-existing igneous and
sedimentary rocks (e.g. limestone  marble)
http://earthsci.org
http://earthsci.org
Metamorphic Rocks
Faulting
Folding
www.dc.peachnet.edu (Charlie Watson)
www.personal.rdg.ac.uk
Metamorphic Rocks
• Fine-grained to coarse-grained
• Generally classified according to texture
Foliated (layered)
parallel layers of
minerals
www.geolsoc.org.uk
www.eos.duke.edu
Non-foliated: no preferred
orientation of minerals
ROCK TEXTURES
METAMORPHIC
www.eos.duke.edu
Foliated
(banded)
Indiana Geological Survey
Metamorphic Rocks
Increasing Temperature & Pressure
• Foliated (layers) metamorphic rock textures:
 Rock cleavage: mica crystals become aligned resulting in
flat surfaces that are parallel (rock tends to split into flat
slabs
http://geology.csupomona.edu
Metamorphic Rocks
Increasing Temperature & Pressure
• Foliated (layers) metamorphic rock textures:
 Rock cleavage: mica crystals become aligned resulting in
flat surfaces that are parallel (rock tends to split into flat
slabs
 Schistosity: mica crystals grow larger giving rock a “platy”
or scaly look
Metamorphic Rocks
Increasing Temperature & Pressure
• Foliated (layers) metamorphic rock textures:
 Rock cleavage: mica crystals become aligned resulting in
flat surfaces that are parallel (rock tends to split into flat
slabs
 Schistosity: mica crystals grow larger giving rock a “platy”
or scaly look
 Banding: light & dark minerals separate giving rock a
banded look
Metamorphic Rocks
http://geology.csupomona.edu
www.geolsoc.org.uk
Metamorphic Rocks
• Nonfoliated metamorphic rock texture:
http:geology.csupomona.edu
Identifying Metamorphic
Rocks
 Identification is based on texture and mineral
composition
Common Metamorphic Rocks
 Gneiss
 Schist
 Quartzite
 Marble
 Serpentine
 Slate
 Amphibolite
http://isaac.exploratorium.edu
www.geophys.washington.edu
http://faculty-staff.ou.edu
Rock Exercise
1. Separate the rocks into igneous, sedimentary and
metamorphic groups (4 each)
2. Identify the rocks using the Rock Name/Description sheet
3. Which of the igneous rocks are intrusive igneous?
Extrusive igneous?
WOW !
Suggested Websites
 www.rocksandminerals.com
 http://nesen.unl.edu
 www.cuug.ab.ca:8001/~johnstos/geosci.html
 www.bced.gov.bc.ca/irp/sciencek7/apf.htm
 www.enchantedLearning.com
 http://volcano.und.nodak.edu/vwdocs/vwlessons/lessons/lesson.
html
 http://fga.freac.fsu.edu/misc/rock.htm
 http://geollab.jmu.edu/Fichter/metaRx/
 http://www.pbs.org
Evaluations